"Most couples are made up of a saver and a spender, so someone is going to complain when the spender spends," said the author of The Family CFO.

Allvine says however, that in these cases, the arguments are seldom about money and instead about values and shared goals. A couple needs to determine what they want out of their money: a home? debt reduction? retirement with travel?

"The commentary is not as much as the $100 you spent but what I thought you could have done with that," she says.

Allvine says the husband spending $100 on golf when the wife thinks it should have to the kid’s summer camp is one example. Or one might hide their shopping bags like they were cheating on the master money plan.

Couples who actually stay together long term find a way to talk about money as a "tool to solve problems or achieve their goals."

To help couples cope, Allvine has 3 basic rules:

Fight about the Right Things
Let your spouse know your money goals and come up with a plan you can both agree on.

Automate Savings
Set aside an agreed amount to pay debt and save and live off the rest.
"You can’t have 10 operating priorities," Allvine says.

Merge Finances
Admittedly this can be a painful process, but Allvine says her studies of couples who keep a "his and hers" system over time can fall short.

Allvine says problems arise when couples face major life changes like having a baby, or one spouse losing a job.

"Just when they need a system of cooperation and benefits of being in a partnership, everything unwinds," she says. "It really turns out to be an avoidance issue, just when you need security your system can betray you."